Several things can dull blades; if you have cut PVC, ABS, or many other plastics, particle board or MDF, then these may have caused the blades to go dull. Cast acrylic will also melt if your feed rate is too slow.
FWIW, all my 10" table saw blades are 80 tooth, they also just go dull over time from cutting lotsa stuff.
For the most part, if your blades are not for acrylic/laminates, they will chip the acrylic rather than melt it. Sounds more like a dull blade to me.
If it is in fact Plex G, then it is definitely cell cast. I do agree with others, no water or other cutting solution should be used on a table saw w/ acrylic.
HTH,
James